Rates of women who are opting for preventive mastectomies, such as Angeline Jolie, have increased by an estimated 50 percent in recent years, experts say. But many doctors are puzzled because the operation doesn't carry a 100 percent guarantee, it's major surgery -- and women have other options, from a once-a-day pill to careful monitoring.

The flu vaccine reduced the chances of illness by just 9 percent in people over 65, the Centers for Disease Control and Prevention reports. Overall, it reduced illness by 56 percent.

Although this year’s vaccine was considered a good match for the most common circulating flu viruses, it still only provided 47 percent protection against the main virus, called H3N2, the CDC said in its weekly report on death and illness.

And that was bad news for people over 65, because it has been an especially tough influenza season.

“The flu season got off to an early start. It was a worse-than-average season but it was particularly severe in the elderly,” CDC spokesman Tom Skinner said in a telephone interview.

It’s killed at least 64 children and is seriously sickening people over 65 at a much higher rate than it did last year — 146 hospitalized per 100,000, as compared to a rate of just 30 per 100,000 last year, the CDC's Lynnette Brammer told a meeting of vaccine advisers on Thursday.

CDC doesn’t count how many adults die from flu each year, because it’s so high – anywhere from 4,000 to 49,000 a year. Last year, 34 children died; 122 died in the especially bad 2010-2011 season and 282 died during the first year of the the H1N1 swine flu pandemic.

Despite its relatively low efficacy, the vaccine likely prevents severe illness than can kill or put people into the hospital, experts say. And vaccinating healthier people can help prevent them from infecting those whose immune systems don’t respond as well to the vaccine.

“While the vaccine is not as effective as we would like, it by far remains the single most important thing people can do to protect themselves from flu,” Skinner said.

Skinner says it’s important for people over 65 to get treated for flu — there’s a pill called Tamiflu and an inhaled powder called Relenza that can help ease symptoms if taken right away.

CDC officials say they don’t fully understand why the flu vaccine works so much more poorly in people over 65 than it does in younger people. Some studies suggest people’s immune response wanes as they get older.

Virtually all health experts agree the influenza vaccines on the market now are far from perfect. “We need better vaccines. The Health and Human Services Department and others are committed to trying to work for a better vaccine,” Skinner says.

CDC says the season appears to have peaked in the third week of January. But influenza can circulate through May, and flu experts note that sometimes a second wave of influenza viruses called influenza B can spread after influenza A viruses, such as H3N2, have waned.

To calculate how well the vaccine worked, CDC experts examined 2,697 children and adults who showed up at the doctor’s office or clinics with flu-like illness.

“Among the patients with influenza, 32 percent had been admin­istered the 2012–13 seasonal influenza vaccine, compared with 50 percent of the influenza-negative controls,” the report reads.

“Vaccine efficacy was estimated as 47 percent against influenza A (H3N2) virus infections and 67 percent against B virus infections.” The annual flu vaccine is reformulated every year; this year’s vaccine targeted three flu strains — one called H3N2, one called H1N1 and an influenza B strain.

The vaccine was 58 percent protective in children, 46 percent effective in young adults, 50 percent effective in people aged 50 to 64 and 9 percent in people 65 and older.

CDC’s Dr. Jeanne Santoli says vaccine makers came up with 145 million doses of flu vaccine this year. She told a meeting of vaccine experts that 138 million doses have been distributed.

Related stories:

Video: CDC: Flu vaccine often doesn’t work

Closed captioning of: CDC: Flu vaccine often doesn’t work

>>>it has so far been an awful
flu season
, and it's not over. and this year, as we seem to do every year, we've been passing on to you the advice of the experts. whatever you do, make sure you get that
flu shot
. well, the new numbers out tonight from the cdc show the
flu vaccine
has actually been a dismal failure among those who need its protection the most. as many as 49,000 americans die from the flu every year, and while we don't have the total numbers for this
flu season
yet, they will be high. and the number of people 65 and over, hospitalized for the flu, has been the highest since they started tabulating in
2005
. our report tonight from our chief science correspondent,
robert bazell
.

>> reporter: it has been the constant message from the cdc throughout this bad
flu season
.

>> reporter: but cdc's own study out today shows that surprisingly often, the vaccine just doesn't work. even though it matched this year's flu strain. overall, the vaccine proved effective, just over half. 56% of the time. but against the dangerous a-strain in people 65 and over, the vaccine offered only 9% protection. in the very
age group
most likely to be hospitalized, and even die.

>>we simply need a better vaccine against influenza. one that works better and lasts longer.

>>over the past decade, the
public health
community has said the
flu vaccine
would be answer. now as we have improved in the science of our studies of
influenza vaccine
, we know that's not the case.

>> reporter: oesterhom and many
public health
officials agree more research is needed to find a better vaccine. meanwhile, they urge people to continue to get vaccinated.

>>although it's far from perfect,
flu vaccination
is by far the best tool we have to protect from flu.

>> reporter: because of the vacci vaccin vaccines' limits, the cdc today made important recommendations for treating people 65 and older. it says they should get treatment with tamiflu or other antiviral medicines if they have suspended influenza, regardless of their vaccination status. critical advice for the population who are usually the most vulnerable to complications from the flu, and after a particularly severe
flu season
, an admission that for them the vaccine often does little good.
robert bazell
, nbc news, new